Heterogeneous phenotypic manifestations of maternally inherited deafness associated with the mitochondrial A3243G mutation. Case report.

The A3243G mutation is one of the most frequent mutations of mitochondrial DNA. The phenotypic expression of the A3243G mutation is variable and causes a wide range of syndromic and non-syndromic clinical disorders. Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome is the most frequent syndromic manifestation of the A3243G mutation. Stroke-like episodes seem to be the dominant feature of MELAS. We have investigated the case of a family with A3243G mutation, in which a dominant symptom in three generations was the maternally inherited hearing loss with absence of stroke-like episodes. Besides deafness, we found also other clinical features such as myopathy, neuropathy, migraine, ataxia, short stature, diabetes mellitus, and cardiomyopathy.